How to Calculate Interest Payments

Not all loans are created equal. Understanding how to calculate a monthly payment, as well as the amount of interest you’ll pay over the life of the loan, are very helpful in choosing the perfect loan for you. Understanding exactly how the money adds up can requires you to work with a complex formula, but you can also calculate interest more simply using Excel.

Steps Edit

Method One of Three:

Quickly Comprehending Your Loan Edit

Method Two of Three:

Calculating your Payment by Hand Edit

Method Three of Three:

Calculating your Interest with Excel Edit

Community Q A

Calculate the first six months of interest at that rate and add it to the principal. Then, continue your calculation using this amount with the adjusted rate of interest.

Typically when you miss a payment the monthly payment amount does not change, but you will be charged a late fee which could be a fixed amount or an amount per day until the payment is made. However, if you do need to calculate the interest on missed payments, you would add the principal amount from the payments you missed and then use that amount in your calculation with the monthly interest rate. A loan amortization schedule will show you exact breakdown of principal to interest for each payment.

A line of credit is not a loan, but the lender’s agreement to provide a loan under certain conditions specified in the line of credit agreement. Lenders usually charge fees for a line of credit since it restricts their lending capacity. However, a line of credit until funded does not provide any cash to repay another loan. As a consequence, it appears that you will need to make a loan to pay off an older loan.

An interest payment is based upon the annual interest rate and the principal amount outstanding for the period. Presuming that you are making interest payments only on a term loan, divide the interest rate stated in the loan documents by the number of payments made in a year. Multiply the result times the principal outstanding. For example, if you have a $10,000 loan at 10% interest, your annual interest payments would total $1,000. If you make quarterly payments, you would pay $250 each quarter.

The ”total” monthly payment (including principal) would depend on the length of the loan. Using “simple” interest, the monthly interest payment would be roughly $85.

This gives you a monthly payment of $17,548.56, using the calculations given in this article. Multiply by 24 payments and you are paying a total of $421,165.44. Subtract that from the original $400,000, and you’re paying a total interest of $21,165.44. Your average monthly interest paid would be around $881.90.

Calculate the interest payments normally, but exclude the irregular ones and add them at the end. For example, if interest is £10 per month for 12 months, but one month it was 9 and one month it was 16, you’d calculate the 10 normal months and add the two irregulars at the end.

Start with the outstanding balance on the loan at the beginning of the current year. Multiply that balance by the loan’s APR (interest rate). Divide that number by 12. That is how much interest you pay in one month.

Leaving aside the complicating question of compound interest (by which your friend would owe you additional interest on all the unpaid interest), you would simply multiply $2500 by 53%. That’s how much interest your friend owes you at this point, in addition to whatever portion of the original principal you expected to get back by now (probably the whole thing!). 1% of $2500 is $25. That makes the calculation easy: your friend owed you $25 in interest every month, or a total of $1,325 over the period of 53 months, plus the original $2500. $25 continues to be added on every month.

That’s 3 percent each year for five years, which amounts to 15 percent simple interest over the whole period. In terms of compound interest, it would be more than that, depending on how often the interest is compounded.

Reusable Spreadsheet to Calculate Interest Payments Edit

The following table details how to use Excel, Google Docs, or similar spreadsheet programs to calculate simply interest payments on anything. Simply fill it in with your own numbers. Note that, where it says F x = , you must fill this part in the upper bar of the spreadsheet labeled “Fx.” The numbers (A2, C1, etc.) correspond to the boxes as they are labeled in Excel and Google Docs.